| Summary: | This paper evaluates the amount of KMnO<sub>4</sub> in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO<sub>4</sub><sup>−</sup> (10<sup>−4</sup>, 10<sup>−3</sup>, 10<sup>−2</sup> mol·L<sup>−1</sup>), corrosion behaviour is examined with regard to hydrogen evolution and composition (protective barrier properties) of forming corrosion products. The corrosion behaviour of HDG samples is evaluated using R<sub>p</sub>/E<sub>corr</sub> and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO<sub>4</sub><sup>−</sup> ion concentration to prevent the corrosion of coating with hydrogen evolution is 10<sup>−3</sup> mol·L<sup>−1</sup>; lower concentrations only prolong the time to passivation (corrosion with hydrogen evolution). The highest used MnO<sub>4</sub><sup>−</sup> concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in Mn<sup>II</sup>/Mn<sup>III</sup> phases.
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